针对物联网中传感网基础设施与应用程序分离将加重安全风险、认证机制不完善等问题,文中基于现存的互联网标准和数据包传输层安全协议DTLS(Datagram Transport Layer Security),提出了一个物联网环境下的端到端双向认证安全机制。该安...针对物联网中传感网基础设施与应用程序分离将加重安全风险、认证机制不完善等问题,文中基于现存的互联网标准和数据包传输层安全协议DTLS(Datagram Transport Layer Security),提出了一个物联网环境下的端到端双向认证安全机制。该安全机制主要利用DTLS协议的全认证握手过程实现对用户和节点身份的双向认证,并对数据进行加密和完整性封装。该机制工作在标准低功耗通信栈上面,在部署了相关协议的传感节点上对安全机制的性能参数进行了评估,如传输延时、能量消耗、内存消耗等。验证其可行性,证明了该安全机制具有低开销和高互操作性。展开更多
A compact interdigital H-mode drift-tube linac (IH-DTL) with the alternating-phase-focusing (APF) method, working at 325 MHz was designed for an injector of a proton medical accelerator. When fed in with a proper RF (...A compact interdigital H-mode drift-tube linac (IH-DTL) with the alternating-phase-focusing (APF) method, working at 325 MHz was designed for an injector of a proton medical accelerator. When fed in with a proper RF (radio frequency) power, the DTL cavity could establish the corresponding electromagnetic field to accelerate the ‘‘proton bunches’’ from an input energy of 3 MeV to an output energy of 7 MeV successfully, without any additional radial focusing elements. The gap-voltage distribution which was obtained from the CST■ Microwave Studio software simulations of the axial electric field was compared with that from the beam dynamics, and the errors met the requirements within ± 5%. In this paper, the RF design procedure and key results of the APF IH-DTL, which include the main RF characteristics of the cavity, frequency sensitivities of the tuners, and coupling factor of the RF power input coupler are presented.展开更多
A multisampling technique was introduced to the phase error detector of Conventional Digital Tanlocked Loop(C DTL). In this new technique a number of samples ( M ) were taken at nonuniform intervals within one peri...A multisampling technique was introduced to the phase error detector of Conventional Digital Tanlocked Loop(C DTL). In this new technique a number of samples ( M ) were taken at nonuniform intervals within one period of the input signal. The novel system is called Multisampling Digital Tanlocked loop(MS DTL). The simulated model on the computer shows that for M =4, the system has a faster locking speed and wider locking in range compared with C DTL.展开更多
The excessive energy of light,especially the invisible rays with lower wavelength,is basically absorbed by retinal pigment epithelium(RPE)and usually causes DNA damage.The molecular mechanism behind DNA damage repair ...The excessive energy of light,especially the invisible rays with lower wavelength,is basically absorbed by retinal pigment epithelium(RPE)and usually causes DNA damage.The molecular mechanism behind DNA damage repair response to this frequent stress in RPE is not clearly understood.In this study,we determined that the Fanconi anemia(FA)pathway was activated in human RPE ARPE-19 cells after ultraviolet(UV)B and C treatment.Moreover,immunoprecipitation(IP)of FANCD2 indicated that denticleless E3 ubiquitin protein ligase homolog(DTL)closely interacted with FANCD2.Knockdown of DTL weakened the activity of the FA pathway in ARPE-19 cells responding to UV treatment.Finally,the DTL promoter was incubated with a biotin-labeled probe and pulled down by streptavidin beads followed by the genomic DNA sonication.p53 was indicated by mass spectrum and further determined by chromatin IP assay.Taken together,our results demonstrated that DTL regulated by p53 could activate the FA pathway for UV-induced DNA damage repair in retinal pigment epithelial cells.展开更多
SSC-LINAC is as a linear injector for the cyclotron accelerator SSC. DTL2 RF cavity is designed to install in SSC-LINAC intermediate energy beam line, whose working frequency is 53.667 MHz and working mode is cw.DTL2 ...SSC-LINAC is as a linear injector for the cyclotron accelerator SSC. DTL2 RF cavity is designed to install in SSC-LINAC intermediate energy beam line, whose working frequency is 53.667 MHz and working mode is cw.DTL2 cavity adopts drift tube structure with IH-mode, which having high shunt impedance, high quality, etc.展开更多
文摘针对物联网中传感网基础设施与应用程序分离将加重安全风险、认证机制不完善等问题,文中基于现存的互联网标准和数据包传输层安全协议DTLS(Datagram Transport Layer Security),提出了一个物联网环境下的端到端双向认证安全机制。该安全机制主要利用DTLS协议的全认证握手过程实现对用户和节点身份的双向认证,并对数据进行加密和完整性封装。该机制工作在标准低功耗通信栈上面,在部署了相关协议的传感节点上对安全机制的性能参数进行了评估,如传输延时、能量消耗、内存消耗等。验证其可行性,证明了该安全机制具有低开销和高互操作性。
基金supported by the National Key Research and Development Program of China(No.2016YFC0105408)
文摘A compact interdigital H-mode drift-tube linac (IH-DTL) with the alternating-phase-focusing (APF) method, working at 325 MHz was designed for an injector of a proton medical accelerator. When fed in with a proper RF (radio frequency) power, the DTL cavity could establish the corresponding electromagnetic field to accelerate the ‘‘proton bunches’’ from an input energy of 3 MeV to an output energy of 7 MeV successfully, without any additional radial focusing elements. The gap-voltage distribution which was obtained from the CST■ Microwave Studio software simulations of the axial electric field was compared with that from the beam dynamics, and the errors met the requirements within ± 5%. In this paper, the RF design procedure and key results of the APF IH-DTL, which include the main RF characteristics of the cavity, frequency sensitivities of the tuners, and coupling factor of the RF power input coupler are presented.
文摘A multisampling technique was introduced to the phase error detector of Conventional Digital Tanlocked Loop(C DTL). In this new technique a number of samples ( M ) were taken at nonuniform intervals within one period of the input signal. The novel system is called Multisampling Digital Tanlocked loop(MS DTL). The simulated model on the computer shows that for M =4, the system has a faster locking speed and wider locking in range compared with C DTL.
文摘The excessive energy of light,especially the invisible rays with lower wavelength,is basically absorbed by retinal pigment epithelium(RPE)and usually causes DNA damage.The molecular mechanism behind DNA damage repair response to this frequent stress in RPE is not clearly understood.In this study,we determined that the Fanconi anemia(FA)pathway was activated in human RPE ARPE-19 cells after ultraviolet(UV)B and C treatment.Moreover,immunoprecipitation(IP)of FANCD2 indicated that denticleless E3 ubiquitin protein ligase homolog(DTL)closely interacted with FANCD2.Knockdown of DTL weakened the activity of the FA pathway in ARPE-19 cells responding to UV treatment.Finally,the DTL promoter was incubated with a biotin-labeled probe and pulled down by streptavidin beads followed by the genomic DNA sonication.p53 was indicated by mass spectrum and further determined by chromatin IP assay.Taken together,our results demonstrated that DTL regulated by p53 could activate the FA pathway for UV-induced DNA damage repair in retinal pigment epithelial cells.
文摘SSC-LINAC is as a linear injector for the cyclotron accelerator SSC. DTL2 RF cavity is designed to install in SSC-LINAC intermediate energy beam line, whose working frequency is 53.667 MHz and working mode is cw.DTL2 cavity adopts drift tube structure with IH-mode, which having high shunt impedance, high quality, etc.
